Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description must cover behavioral traits. It mentions return format but does not disclose precision, unit handling, behavior for invalid parameter combinations, or whether the operation is read-only. The description is adequate but lacks deeper context.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is concise with two sentences: first states purpose, second gives return and reference. No unnecessary words, well-structured.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given 8 parameters with complex shape-dependent logic, the description does not explain which parameter combinations are valid for each shape (e.g., rectangle needs length and width). The output schema is described but parameter usage details are missing, making it moderately incomplete.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so baseline is 3. The description adds minimal value beyond schema, only noting the return format. It does not clarify parameter relationships (e.g., which params for each shape), which is a gap given the shape-dependent logic.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool calculates perimeter/circumference for common shapes and specifies the return format {shape, perimeter}. It distinguishes from siblings by referencing 'common shapes' and directing to list_bundles for related calculators.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides minimal usage guidance, only mentioning list_bundles for related calculators. It does not specify when to use this tool versus specific alternatives or provide exclusions, which is insufficient given the large number of sibling tools.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.